Termites in Arizona: seventeen species, and the three that matter

Search for what termites look like in Arizona and you will be told there are three types. Or four. The pages saying so do not agree with each other and none of them cites anything. The real number, from the University of Arizona, is that at least seventeen termite species live in this state and only three are of any significant economic importance — and the one you are most likely to actually notice is not among them. This page is about telling them apart before anybody sells you a treatment.

Seventeen species, and the three that matter

Worldwide there are roughly 2,761 named termite species across 282 genera. About forty-five of those occur in the continental United States, and close to thirty of them damage wood or wood products. Arizona holds at least seventeen. Three of them are worth a homeowner’s attention, and the University of Arizona’s Cooperative Extension is blunt about the rest.

Everything gets sorted into three groups by where it lives: dampwood, drywood and subterranean. In Arizona the dampwood group is not a widespread problem, drywood turns up under particular conditions, and the subterranean group is what the Extension calls one of our major urban pests. Termites in general it ranks as Arizona’s number one urban pest, which is not a sentence written about scorpions or roaches.

The arid-land species explains something people find unfair. It lives out in the desert quite happily on creosote and greasewood bushes. Build a house on that ground, clear the creosote, and you have removed the food supply from an established population that is still there. The structure is what is left.

That is worth sitting with, because it reframes the whole subject. A termite problem in a new Valley subdivision is not usually something that arrived. It is something that was already living on that half-acre before anyone graded it, eating creosote, and then had its diet replaced with a house. Which is also why the age of the building tells you far less here than people expect, and why a property built in the last fifteen years is not automatically safer than one built in the seventies.

The one you are most likely to see, and why it is harmless

Here is the part that saves people money, and it is the reason this page exists.

There is a fourth termite out there called Gnathamitermes perplexus, and depending on the survey it is either the most common or the second most common termite in Arizona. It is also the one you are most likely to spot with your own eyes, because of what it builds. It feeds on dead plant material — desert plants, dead grass, twigs, fence timber, even dried cow dung — and it works by laying a thin, pale, plaster-like coating of earth over the surface and scraping the dead wood away underneath.

So you walk out one morning and find a wooden fence post, a palm trunk or a patch of dead grass wearing a crust of dried mud. Break a piece off and small pale insects scatter and vanish into the ground. It looks exactly like what everybody has told you to dread.

It is not a structural pest. The Extension’s position is plain: these termites are not pests and should not be treated for unless they are found inside a structure. They are doing in your garden exactly what they do across every square mile of desert around it, which is recycling dead plant material. If the mud crust is on a fence, a palm or the ground, the honest answer is to leave it alone.

There is even a way to confirm it under magnification, if you are the sort of person who owns a hand lens. The soldiers of this species have jaws that curve inward and carry an obvious tooth on the inner edge. That tooth is the feature used to separate the harmless desert termite from the damaging ones, whose jaws are slender and nearly straight.

Telling a termite from a flying ant

This is the single most common identification question in the category, and it is settled by two features you can see without any equipment at all.

Termites are sometimes called white ants, which is unhelpful on both counts, but the nickname does point at something true: a pale insect that looks ant-shaped and is coming out of a tube of mud is a termite, because ants do not build those.

What the different castes look like

A colony is not one kind of insect. It contains three, they look nothing alike, and knowing which one you are holding changes what it tells you.

Workers are what almost every homeowner actually sees — pale, soft, small, and the ones doing everything. They build and repair the tunnels, forage, feed the colony, groom each other and help the others through each moult. If you break open a mud tube, these are what pour out.

Soldiers exist to defend against ants and against termites from other colonies, and they do it with a pair of large opposing jaws. They are also the caste that matters most for identification, which is why anybody serious about naming your species will ask for soldiers rather than workers. On the two damaging subterranean species the jaws are slender and close to straight, and separating those two from each other properly means examining the mandibles in detail — they are genuinely difficult to tell apart.

Reproductives, also called alates, are the winged adults that leave to start new colonies. They range from light tan through reddish brown to nearly black depending on species, have properly developed eyes, visible jaws and membranous wings. They are the ones that end up on your porch, and they are the second-best specimen for identification after a soldier.

One figure worth holding on to, because it reframes a swarm from a disaster into an event: of the millions of alates that fly in Arizona every year, usually fewer than one per cent survive to found a colony. A cloud of them at your window is not a cloud of future infestations.

Mud tubes, pellets and what each one tells you

The swarm calendar, and what the timing alone tells you

This is the part almost nobody writes down, and it is the most useful thing on this page after the harmless-species section. In Arizona, when the winged adults appear narrows down what they are before anyone looks at an insect.

The harmless desert termite flies too, usually after a summer rainstorm, and does it in the morning or evening rather than the middle of the day. So a July swarm after rain could be either the species that will eat your roof timbers or the species quietly recycling your fence. That is precisely why the insect itself still has to be looked at — but the calendar has already cut the field down.

One behaviour links all of them: the alates are drawn to lights, and that is where pairing starts. A porch light during a swarm window is the reason they arrive at your door rather than somebody else’s, and shed wings on a windowsill or in a pool skimmer are often the first evidence anybody finds.

Looking for them on a Phoenix house

If you want to check your own property, there are four places worth a torch and ten minutes, and they are not evenly likely.

Start at the foundation wall where it meets the soil, and walk the whole perimeter looking for tubes running up the stem wall. Then the cracks in concrete floors, and every point where a pipe or a duct comes up through the slab — those penetrations are a route in and they are easy to overlook in a garage or a utility cupboard. Then door and window joinery, looking for small heaps of dry pellets rather than tubes. And finally the wood itself: tap along it every few inches with a screwdriver, listening for a hollow note, and in a badly damaged section the screwdriver may go through into the galleries.

Termites are secretive by nature and spend nearly all their lives inside soil or inside wood, so a clean ten-minute inspection is reassuring rather than conclusive. What it is very good at is finding the obvious thing early, which is the difference between a contained problem and an expensive one.

Two habits make that ten minutes worth far more. Do it at the same time each year rather than when something worries you, because what you are really looking for is change — a tube that was not there last spring means something a tube you have never looked for does not. And when you photograph something ambiguous, lay a ruler or a key alongside it. Size does an enormous amount of the work here — a quarter-inch body and a half-inch body belong to different groups entirely — and a close-up with nothing around it for reference throws that information away. A shot that includes the surrounding timber or wall is worth more than a sharper one that does not.

What to do when you find something

The first instinct is usually to take a photograph and the second is to spray something. Reverse them, and do neither until you have done this. Collect it, and collect the right thing. Soldiers are the most useful specimen and winged adults the next most useful; workers, which are what you will most easily catch, are the hardest to name. Drop them into alcohol rather than trying to keep them alive, and note exactly where they came from, because a tube on a stem wall and a pile of pellets under a window mean different species and different conversations.

Then do nothing in a hurry. Termites are slow — structural damage generally takes years, not weeks, which is the one genuinely calming fact in this subject. That is time enough to identify what you have properly and get more than one opinion, and it is why the Extension advises against trying to treat them yourself.

If it does turn out to be one of the three that matter, our termite control page sets out what treatment actually involves and the two routes you might be offered, and the termite inspection page covers what an inspection includes and when Arizona requires a formal report. If you are still not sure what you are looking at, the pest identification guide covers the rest of what turns up in a Phoenix house.

Termite identification questions

Related services